#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define vl vector<ll>
#define vi vector<int>
#define pb push_back
#define sz(v) (ll)(v.size())
#define f first
#define s second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
const ll mod = 1e9+7;
void solve()
{
ll h, w, i, j;
cin >> h >> w;
ll dp[h+5][w+5];
for(i = 0; i <= h + 1; i++)
{
for(j = 0; j <= w + 1; j++)
{
dp[i][j] = 0;
if(!i || !j)
dp[i][j] = 1;
}
}
for(i = 1; i <= h; i++)
{
for(j = 1; j <= w; j++)
{
dp[i][j] += dp[i-1][j];
dp[i][j] %= mod;
dp[i][j] += dp[i-1][j-1] * 4 * j;
dp[i][j] %= mod;
if(j >= 2){
dp[i][j] += dp[i-1][j-2] * ((j * (j - 1)) / 2);
dp[i][j] %= mod;
}
if(i > 1){
dp[i][j] += dp[i-2][j-1] * j * (i - 1);
dp[i][j] %= mod;
}
}
}
dp[h][w]--;
if(dp[h][w] < 0)
dp[h][w] += mod;
dp[h][w] %= mod;
cout << dp[h][w] << "\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
ll tests = 1;
//cin >> tests;
while(tests--)
{
solve();
}
}
